I too would recommend to use GNU/Linux not only for BTC but for everything else as well. While GNU/Linux might be even unsafer especially when used by a newbie its smaller userbase makes it currently a less attractive target for malware. When you use Windows you use a Blackbox and have to trust MS and all those providing Applications for Windows blindly. My main PC is a Box with Debian Linux and I never had a problem in years (I started using Linux back in 1995). I also have to use Windows for work everyday but I can't say I never had an issue with it.